Variable resistance device for an exercise machine

ABSTRACT

The invention concerns novel pharmaceutical compositions capable of comprising micelles containing at least a very lipophilic principle enabling to enhance bioavailability of active principles insoluble in aqueous solvents called MIDDS® (Micellar Improved Drug Delivery Solutions).

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a variable resistance device adapted tobe incorporated in an exercise machine to provide a selectively-variabledegree of resistance for the exercise machine.

2. Description of Prior Art

An exercise machine, by definition, needs to provide the user with adegree of resistance for muscular exercise. In almost all forms ofexercise, there is a requirement in exercise machines for the degree ofresistance to be varied.

First, there is the need for the user to vary the degree of resistancewith a minimum of effort and complexity.

Second, another need is for the selected degree of resistance to beprecise and repeatable. This is particularly so for resistance machinesused by athletes who require a precise calibration of resistance valuesso that the values can act as a precise reference point for monitoringtheir exercise routines. As an example, sporting institutions wouldbenefit from a precisely calibrated exercise machine for testing largenumbers of athletes over a long period of years, so that there can beconfidence that the degree of resistance used in a set of test exercisescan be guaranteed to remain constant over the period of years. Thisdegree of repeatability is often difficult to maintain, for instance, inexercise machines that use magnetic resistance, and wind resistance. Inthe case of magnetic resistance, the calibration of the magnets canalter over time. Wind resistance can be affected by the amount ofatmospheric pressure, particularly when the same machine is used atdifferent altitude levels.

There is also the need for the user to selectively change the degree ofresistance, even within a workout. In PCT/US88/01580, InternationalPublication W088/08735 (Duke), an exercise machine, which simulatesrowing, is provided with a resistance device which consists of a paddlethat rotates in a cylindrical water-filled container. The degree offluid in the container determines the degree of resistance experiencedby the user. This prior art machine is provided with a handle connectedto a drive cord. The user pulls and releases the drive cord, therebysimulating the stroke an oar when rowing a boat. However, in this priorart device, resistance is varied by a cumbersome method of wrapping agreater or lesser quantity of strap around the drive spool. It isbelieved that this increases or decreases the tangential forces as thecircumference is increased or decreased.

Moreover, this manner of varying the resistance does not readily providean accurate repeatable degree of resistance, since the user might notknow how much cord has been wrapped, nor how much cord remainsunwrapped. Also, the range of resistance-afforded by wrapping andunwrapping a cord-is narrow in range, so that the user does not have thebenefit of using a wide range of resistance values.

In the prior art, which relate to resistance in the form of paddles thatrotate in baths of water, there are systems which involve a first andsecond chamber, wherein liquid is transferred between the chambers so asto vary the amount of liquid in the primary container in which thepaddle rotates, for example U.S. Pat. No. 5,944,637 (Stickler), and U.S.Pat. No. 5,195,936 (Mao). In these prior art, however, the liquid isforced from a first chamber into a second chamber through the sameaperture or apertures. In other words, there is a two-way flow of liquidthrough the same aperture. Thus, these prior art apparatus must beprovided with complex mechanisms needed to force the liquid through thesame aperture, initially, in a first direction, then back through thesame aperture in a second direction. The need for applying such forcesmeans that the exercise machines require complex and thus more expensivemechanisms to force the liquid in and out of the apertures which linkthe chambers.

An objective of the present invention is to overcome or at leastameliorate one or more of the above problems in the prior art, or toprovide an improved alternative.

BRIEF SUMMARY OF THE INVENTION

According to the present invention, there is provided a variableresistance device adapted to be incorporated in an exercise machine toprovide selectively variable resistance therefor, the device including:a primary fluid chamber adapted to receive fluid therein, the primarychamber having a primary fluid flow region; a rotation mechanismpositioned and adapted to rotate within the primary fluid flow regionsuch that the rotation mechanism upon rotation encounters a degree ofresistance dependent on the amount of fluid in the primary fluidchamber, the rotation mechanism being adapted to be rotated byrotational input from the exercise machine; a secondary mechanismadapted to achieve and maintain an appropriate amount of the fluid inthe primary fluid chamber to provide a selected degree of resistance forthe exercise machine, the secondary mechanism having a secondary fluidflow region; a fluid flow circuit, which includes said primary andsecondary fluid flow regions, through which circuit the fluid flows toestablish a circuit-flow condition that repetitively cycles around thecircuit from the primary fluid flow region into the secondary fluid flowregion and then back into the primary fluid flow region, thecircuit-flow condition being adapted to establish and maintain saidappropriate amount of fluid in the primary fluid chamber during use; anda variation means or controller for variably controlling flow of fluidthrough the circuit to selectively establish different circuit-flowconditions each corresponding to a different appropriate amount of thefluid in the primary fluid chamber to provide a different degree ofresistance for the exercise machine.

Preferably, the secondary mechanism includes a secondary fluid chamberadapted to receive fluid therein, the secondary fluid chamber havingsaid secondary fluid flow region.

Preferably, the amount of fluid in the primary fluid chamber is able tobe ascertained by measuring the level of fluid in the secondary fluidchamber.

In one embodiment, the secondary fluid chamber may be positionedexternally to the primary fluid chamber.

In other embodiments, the secondary fluid chamber may be positionedinternally within the primary fluid chamber.

Preferably, the primary fluid flow region of the primary fluid chamberis defined by inner surfaces of the primary fluid chamber and by outersurfaces of the secondary fluid chamber.

Preferably, the inner surfaces of the primary fluid chamber form a firstcircle, and the outer surfaces of the secondary fluid chamber form asecond circle which is concentric and c-axial with the first circle, theprimary fluid flow region being generally between the two circles.

Preferably, the primary fluid flow region generally surrounds thesecondary fluid chamber.

In one embodiments, the primary fluid flow region may be arrangedsubstantially horizontally.

Preferably, the primary fluid flow region further includes a space whichis within the second circle and which is beneath the secondary fluidchamber, the space defining a gap between an external undersurface ofthe secondary fluid chamber and an inner surface of the primary fluidchamber.

In some embodiments, the gap may be insufficient for a fluid whirlpoolto be created under the secondary fluid chamber when the fluid flows inthe primary fluid flow region.

In some embodiments, the primary fluid flow region may be arrangedgenerally upright.

In an example of the upright embodiment, in use, when the user providesthe rotational input, the fluid moves around the primary fluid flowregion of the primary fluid chamber and also through the fluid flowcircuit, and when the user ceases providing the rotational input, thefluid in the uprightly-oriented primary chamber falls to bottom of theprimary fluid chamber thereby acting as a body of fluid that stops therotation of the rotation mechanism.

In some embodiments, the inner surfaces of the primary fluid chamberand/or the outer surfaces of the secondary fluid chamber may be providedwith baffles to hinder the flow of fluid in the primary fluid chamber.

Preferably, the gap is sufficient for a fluid whirlpool to be createdunder the secondary fluid chamber when the fluid swirls around in theprimary fluid flow region, the primary fluid flow region being shaped sothat the whirlpool is able to continue swirling freely even aftercessation of the input from the exercise machine to the rotationmechanism.

Preferably, the secondary mechanism is provided with inlet means thatallows fluid to flow from the primary flow region into the secondaryflow region.

Preferably, the variation means variably controls the flow of fluidthrough the inlet means.

Preferably, the secondary mechanism is provided with outlet means thatallows fluid to flow out of the secondary flow region back into theprimary flow region.

Preferably, the variation means variably controls the flow of fluidthrough the outlet means.

Preferably, the variation means variably controls the flow of fluidthrough the outlet means by raising or lowering the height position ofthe outlet means.

Alternatively, the variation means variably controls the flow of fluidthrough the outlet means by increasing or decreasing the flow-throughsize of the outlet means.

The fluid may be water or other suitable fluid.

Preferably, the fluid flow circuit is open to the atmosphere and is notof a hydraulic-nature.

Preferably, the fluid in the fluid flow circuit is constant in amount.

The rotation mechanism may be directly connected to the rotational inputfrom the exercise machine without the need for a transmission and/orstep-up system.

The exercise machine, for example, may be an exercise bicycle, or arowing-simulating exercise machine.

In some embodiments, a transmission arrangement may be provided to alterthe rate of rotation from the exercise machine such that the rotationmechanism receives a different rotational rate of input.

According to another aspect of the invention, there is provided asimilar variable resistance device except that, instead of including therotation mechanism, a reciprocating mechanism is positioned and adaptedto reciprocate within the primary fluid flow region such that thereciprocating mechanism upon reciprocation encounters a degree ofresistance dependent on the amount of fluid in the primary fluidchamber, the reciprocating mechanism being adapted to be reciprocate bymechanical input from the exercise machine.

A more detailed explanation of the invention is provided in thefollowing description and appended claims taken in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the present invention might be more fully understood,embodiments of the invention will be described, by way of example only,with reference to the accompanying drawings, in which:

FIG. 1A illustrates an embodiment of an external cover member for aprimary fluid chamber;

FIG. 1B illustrates a secondary fluid chamber surrounded by a rotatingset of vanes, except with the cover member removed to show the inside ofthe secondary chamber and with the side wall of the primary chamber alsoomitted for clarity;

FIG. 1C is an exploded view of various components of the variableresistance device;

FIG. 1D is a schematic view of overlapping openings in cylindrical wallsof inner and outer parts of a value assembly shown in FIG. 1C;

FIG. 1DD is a schematic view identical to FIG. 1D save that the twoopenings shown have a different degree of overlap;

FIG. 2A is similar to FIG. 1A, accept that the second embodiment relatesto a vertical or upright configuration;

FIG. 2B illustrates a vertically-oriented secondary chamber surroundedby a rotatable set of vanes; except with the cover member removed toshow the inside of the secondary chamber and with the side wall of boththe primary and secondary chambers also omitted for clarity;

FIG. 2C illustrates an exploded view of various components of thevertically-oriented embodiment of a variable resistance device;

FIG. 3A illustrates a cross-sectional view of a horizontal embodiment ofa variable resistance device;

FIG. 3B illustrates the embodiment of FIG. 3A except shown with thedynamic fluid flow condition illustrated with arrows;

FIG. 3C relates to an expanded detail of a section taken from 3B;

FIG. 4A relates to a cross-sectional side view of a vertically-orientedembodiment of a variable resistance device;

FIG. 4B relates to the embodiment of FIG. 4A, accept with the dynamicfluid flow condition illustrated notionally with small arrows;

FIG. 5 relates to a further modification of a vertically-orientedembodiment in which the secondary chamber is external to the primarychamber;

FIGS. 6 to 11 illustrate the incorporation of embodiments of thevariable resistance device in various types of different exercisemachines;

FIG. 12A illustrates a horizontal embodiment of a variable resistancedevice, in which the diagram has been simplified in order to highlightprincipals of operation of the device; and

FIG. 12B illustrates a vertical embodiment of a variable resistancedevice in which the diagram has also be simplified in order to highlightthe operating principle.

The diagrams in FIGS. 12B and 12A show embodiments illustrated in asimplified form merely in order to facilitate understanding of thefunction of various embodiments of the invention, and that the actualconfiguration of exemplary embodiments of these items are more fullyillustrated in FIG. 1A to FIG. 11.

In the drawings, like components, or those with analogous function, arereferred to with like numerals, merely for ease of understanding thedescription.

For this reason, some components with different shape and configuration,in the various embodiments, have been provided with the same referencenumerals in the drawings to aid understanding of the specification.

In the drawings, the relative dimensions of some of the components havebeen exaggerated in size merely for clarity in understanding thedrawings.

In FIGS. 3A, 3B, 4A, 4B and 5, the grid of dotted lines serve toindicate examples of liquid levels.

DETAILED DESCRIPTION OF THE INVENTION

A detailed description of the preferred embodiments and best modes forpracticing the invention are described herein.

Before describing some exemplary embodiments in detail in relation toFIGS. 1A to 11, first of all, for the sake of ease of understanding theoverall concepts, reference is made first to the simplified drawings inFIGS. 12A and 12B.

Incorporation In Exercise Machines

FIG. 12A relates to a simplified diagram showing components of anembodiment of a variable resistance device 100. The device 100 isadapted to be incorporated in an exercise machine in order to provideresistance against which the user performs the exercise on the machine.The device 100 may be incorporated in a range of exercise machines, forexample, such as the machines in FIGS. 6 to 11.

FIGS. 6 and 7 show the variable resistance device 100 incorporated inexamples of exercise machines. For instance, FIGS. 6 and 7 show thedevice 100 in a rowing-simulating machine, with the device 100 beingarranged respectively upright and horizontally.

FIG. 8 shows the device 100 incorporated in a running-simulating machinein the form of an elliptical stepper machine.

FIG. 9 shows the device 100 incorporated in a upper-body exercisemachine.

FIG. 10 shows the device 100 in a seated-pedaling machine, known as arecumbent cycle.

FIG. 11 shows the device 100 incorporated in a stationary exercisebicycle, known as an upright cycle.

The embodiments of variable-resistance devices can be incorporated intothese known exercise machines using known linking mechanisms, and hencethe present invention is not restricted to any one form of linkingmechanism. The function of a linking mechanism is merely to translaterotational input, generated by the user's exercise motion, to causerotation of a rotation mechanism in the device 100. The rotationmechanism is rotated by rotational input from the exercise machine. Thelinking mechanism is not part of the present invention, and would beregarded more appropriately as part of the exercise machine itself.

An example of an exercise machine linked to a prior art resistancedevice is found in PCT/US88/01580, International Publication Number WO88/08735 in the name of Duke. The details of the Duke machine andlinking mechanism are incorporated into this present description byreference, but merely as an example of an exercise machine and a linkingmechanism. There is no inference that the variable resistance device ofthe present invention is disclosed in the Duke prior art.

A further example of an exercise machine is U.S. Pat. No. 4,396,188 inthe name of Dreissigacker, which relates to an exercise machine thatuses a rotatable fan-type flywheel, relying on air-resistance. Thedetails of the Dreissigacker machine and linking mechanism areincorporated into this present description by reference, but merely asanother example of a different exercise machine and linking mechanism.There is no inference that the variable resistance device of the presentinvention is disclosed in the Dreissigacker prior art.

The variable resistance device of the present invention is adapted to beincorporated in a range of exercise machines, and is not limited to aparticular exercise machine or linking mechanism.

The rotation input from the exercise machine can be directly coupled tothe rotational mechanism in the form of a rotating spindle 30 having aset of rotating vanes 2 which rotate about a common axis of the spindle.In FIG. 2C, the axis of the spindle fits through a hole 13 in the base12 of the primary chamber 1.

The rotation mechanism is directly connected to the rotational inputfrom the exercise machine. Some embodiments may or may not require atransmission and/or step-up system.

The speed of rotation depends to an extent on the nature of theparticular exercise machine. Some direct drive machines, such as the armrower of FIGS. 6 and 7, would be used at rotational speeds of 30 to 100r. p. m. Others exercise machines require ramped up transmission drivecycles that enable rotation speed of 60 to 100 r. p. m., generated bythe user's body motion, to be translated or stepped up to rotationalspeeds of 600 to 1000 r. p. m.

The large amount of liquid in the overall device 100 acts as a coolantwhich absorbs any heat that may be generated from the work associatedwith rotation.

Some embodiments of the invention do not require a transmission or stepup system, because the rotational speed achieved by a user, forinstance, pedaling an exercise bicycle is around 60 r. p. m. or so, evenup to around 100 r. p. m., which is suitably in the range of speeds atwhich the present embodiments can operate. In contrast, other resistancemechanisms, such as friction belts, tend to be jerky at such slowrotation speeds, because sufficient speed is required to overcome theinitial resistance inherent in these systems. Magnetic resistancesystems also require sufficient rotational speed. Whereas, the presentembodiments are suitable for operating at rotation speeds that canreadily be achieved by human muscle power. Also, the present embodimentsare suited for direct drive connection to the exercise machine becausethe degree of resistance provided by liquids, such as water, are of theorder of magnitude that can be directly used for exercise. In contrast,the resistance offered by other prior art systems, such as magnetic orair resistance, are usually much higher or lower than the range ofresistance preferred by users. Hence, some form of transmission isrequired to increase or decrease the load. Hence, in those prior artsystems, direct drive is rarely feasible. Thus, the present embodimentsare ideally suited for direct drive connections, thus avoiding thehigher cost and size associated with transmission step-up systems.

An advantage of direct drive systems is that there is less “ramp up”required for the user to overcome, since the user initiates the exerciseby starting the swirl the fluid or water in the primary chamber 1,whereas in transmission drive systems there is often a substantialdegree of inertia and a degree of friction inherent in the resistancecomponents, such as the magnetic resistance components or the belt drivecomponents. For example, it can be appreciated that it would be easierfor a user to start swirling a paddle in water, compared with overcomingthe initial friction of a belt drive system. Thus, direct drive systems,for which the present embodiments are well suited, are ideal forexercise machines used in rehabilitation programs where the users oftendo not have normal muscle function, which causes the initial “ramp up”of prior art systems to pose a problem, which would not be the case forhealthy users.

Thus, those embodiments of the invention that are used in direct drivesystems are particularly useful for rehabilitation exercise programs.Direct drive embodiments are also useful for rowing-simulating exercisemachines.

Alternatively in other embodiments, however, a variable transmissiondevice may be used to connect the rotation input to the rotating spindle30, so as to adjust the ratio of the relative rotational speeds. This isparticularly the case for exercise machines for general use, since someforms of exercise may not generate sufficient rotational speed togenerate a suitable degree of resistance from the resistance device 100.

In the embodiments where there is a direct drive connection, the absenceof a transmission mechanism allows the exercise machine to cost less andbe simpler to manufacture.

Provision of Resistance

The present embodiment of the variable distance device 100 provides arange of different degrees of resistance that can be varied selectivelyby the user.

In FIG. 12A, the device 100 includes a primary fluid chamber 1 which isshaped as a squat cylindrical chamber with a base 12, filled with anamount of fluid (the fluid level is not shown in the diagram). In thissimplified diagram of FIG. 12A, the primary chamber 1 is arrangedgenerally horizontally.

The rotating vanes 2 rotate within the primary chamber 1. The vanes 2rotate in the liquid flow region of the primary chamber 1 such that thevanes encounter a degree of resistance dependent on the amount of fluidin the primary chamber 1. A more detailed illustration of the vanes 2 isin FIG. 1C.

In FIG. 12A, the vanes 2 rotate about the central axis of a transmissionshaft or spindle 30. In this embodiment, the spindle 30 is orientedupright or vertical.

The spindle 30 is connected to a linking mechanism of the exercisemachine. The spindle 30 receives rotational input from the exercisemachine via the linking mechanism. In use, the exercising action of theuser on the exercise machine is translated, by the linking mechanism,into rotational motion of the vanes 2.

A more detailed illustration of the embodiment of FIG. 12A is shown inFIG. 3A.

In FIGS. 3A and 12A, in order to provide a degree of resistance for theuser's workout, the primary chamber 1 is filled with an amount of fluidwhich resists the rotation of the vanes 2. (The fluid level isillustrated as dotted lines in FIG. 3A).

Having described the simplified diagram of FIG. 12A, fuller illustrativedetails are shown in FIGS. 1A to 1C. FIG. 1A shows a fully assembledprimary chamber 1. The primary chamber 1 is supported on a support beam7.

FIG. 1B shows the primary chamber 1 containing the rotatable vanes 2.FIG. 1B shows the arrangement with the lid of the primary chamberremoved to reveal the secondary chamber 3, having an inlet 5 and anoutlet 6 incorporated in parts of a valve having an outer cylinder 9.(Note: in FIG. 1B as drawn, the upright side walls of the primarychamber 1 have been omitted to reveal the other components, and only thebase 12 of the primary chamber 1 is shown).

Variation of Resistance

The degree of resistance, encountered by the rotating vanes 2, isdependent on the amount of fluid in the primary chamber 1. For instance,when there is a low fluid level in the primary chamber 1, the vanes 2encounter a low degree of resistance. Conversely, if the primary chamber1 has a greater amount of fluid, the vanes 2 encounter a higher degreeof resistance.

In FIG. 12A, the amount of fluid in the overall device 100 is keptconstant. Thus, changes in the amount of fluid in the primary chamber 1is achieved by maintaining part of the total in a secondary mechanismhaving a secondary fluid chamber 3. The secondary mechanism achieves andmaintains an appropriate amount of the fluid in the primary chamber 1 toprovide a selected degree of resistance for the exercise machine.Therefore, in order to vary the fluid level in the primary chamber 1, i.e. to vary the resistance, part of the fluid is held in the secondarychamber 3.

In the embodiment, the secondary chamber is motionless with respect tothe primary chamber 1.

For illustration, if there are 10 litres of fluid in the overall device100, then establishing and maintaining an amount of seven litres in thesecondary chamber 3 will ensure that only three litres remain in theprimary chamber 1. Hence, these three litres of fluid will provide arelatively low degree of resistance.

If the user wishes to increase the resistance offered by the device 100,he alters the fluid flow through the circuit to establish a differentcircuit flow condition in which, for instance, four litres are retainedin the secondary chamber 3, thus leaving six litres in the primarychamber 1. Hence, there is now double the amount of fluid in the primarychamber 1, which results in an increased degree of resistance affordedfor the user's workout.

In the exemplary embodiments, the overall resistance device may containaround 14 litres of water. A user typically rotates the vanes 2 ataround 60 r. p. m., which is around one cycle per second. Without beingbound by particular experimental results, it is believed that around 7litres of water can be moved around the circuit in around seven seconds.In exemplary embodiments, a rate of transfer of 1 litre per second, maybe achieved between the primary and secondary chambers 1,3. Hence, theappropriate level of fluid needed for a particular degree of resistancecan be established fairly rapidly.

In another example, in a non-limiting embodiment which houses 10 litersof fluid, changes in resistance were found to be surprisingly fast.Increases up to the maximum resistance level seem to the user to bealmost instant. In the embodiment, decreases in resistance level alsoappeared to user as being almost instant. For example, decreases of overhalf of the possible resistance range were achieved by a few slow cyclesof the flywheel taking no more than a few seconds.

In various embodiments, the size and location of the inlets and outletsof the device, and other size parameters, can be varied, with someexperimentation, to achieve the desired degree of flow rate around thecircuit, for example 1 litre per second.

Fluid Flow Circuit

Fluid flowing continuously between the primary 1 and secondary chambers3 via a fluid flow circuit which includes those parts of the primary 1and secondary 3 chambers through this fluid flows.

Fluid flows through the fluid flow circuit to establish a circuit-flowcondition that cycles around the circuit repetitively from the primaryfluid flow region into the secondary fluid flow region and then backinto the primary fluid flow region and so forth. The circuit-flowcondition establishes and maintains the appropriate amount of fluid inthe primary chamber during use.

In the embodiment, the fluid flow circuit is open to the atmosphere andis not of a hydraulic-nature. In hydraulic systems, the hydraulic fluidmust be pushed or forced through a closed system using a pump, whereasin the present embodiments the fluid is not pushed or forced. Inhydraulic resistance exercise systems, resistance is regulated byrestricting fluid flow, requiring the user to exert a greater amount ofpressure on the hydraulic fluid to force the fluid through the hydrauliclines. In contrast, in the present embodiments, there is a naturalcircuit flow condition that is achieved as a result of the configurationof the components, and of the rotation of the vanes. There is, thus, noneed for expensive devices that would otherwise be necessary for forcingpressurized hydraulic fluid. The embodiment can therefore be constructedless expensively since the need for strong pressurised containers,required for hydraulic systems, is avoided.

The primary chamber 1 has a fluid flow region that is defined by innersurfaces of the primary fluid chamber 1 and by outer surfaces of thesecondary fluid chamber 3.

The inner surfaces of the primary fluid chamber 1 form a first circle,and the outer surfaces of the secondary fluid chamber 3 form a secondcircle which is concentric and c-axial with the first circle. Theprimary fluid flow region is generally between the two circles. Theprimary fluid flow region thus generally surrounds the secondary fluidchamber 3.

In the embodiment where the secondary chamber 3 is located within theprimary chamber, an advantage is that a variable resistance capabilityis provided without an overall increase in the size dimensions of theresistance device.

In the embodiment in FIG. 12A, the primary fluid flow region furtherincludes the space which is within the second circle and which isbeneath the secondary fluid chamber 3. The space defines a gap A betweenan external undersurface of the secondary chamber 3 and an inner surfaceof the primary chamber 1.

It is important that a fluid flow circuit is established between theprimary 1 and secondary 3 chambers. The fluid flow circuit is shown inFIG. 3A as a series of arrows.

In simplified FIG. 12A, the flow of fluid through the circuit isexplained as follows: Fluid is initially contained in the primarychamber 1. As the vanes 2 spin around the spindle 30, turbulence iscreated in the primary chamber 1.

The secondary chamber 3 is provided with inlet means in the form ofinlet 5. The inlet 5 allows fluid to flow from the primary flow regioninto the secondary flow region. The turbulence causes a portion of thefluid to enter the inlet 5, so that the secondary chamber 3 begins tofill with fluid. However, upon entering the secondary chamber 3, part ofthe fluid is able to leave the secondary chamber 3 through outlet meansin the form of outlet 6. The outlet 6 allows fluid to flow out of thesecondary flow region back into the primary flow region. Fluid leavingthe secondary chamber through outlet 6 returns to the primary chamber 1.Thus, the fluid cycles around the fluid flow circuit, never returningvia same path. In other words, for example, liquid flows through theoutlet 6 only in one direction, which is from the secondary 3 into theprimary chamber 1.

In FIG. 12A and FIGS. 3A, and 3B, the side walls of the secondarychamber 3 are inclined and taper towards the base of the chamber 3. Thisallows the inlet 5, which in the embodiment is located close to theupper rim of the chamber 3, to be positioned as close as possible to theinner side wall of the primary chamber 1. This positioning is because ofthe fact that, during rotation, it is observed that much of the swirlingfluid flows along the circumference of the inner side wall, so thepositioning of the inlet 5 as close as possible to this location ensuresit is located to readily receive fluid. A similar design rationale isfound in the upright or vertical embodiments of FIGS. 4A and 4B.

In the horizontally-oriented embodiment of FIG. 3B, it can be seen theinlet 5 is positioned at the upper edge of the secondary chamber 3. Thereason for this location is because, as the liquid in the primarychamber 1 is stirred by the vanes 2, the tendency is for some of thefluid to be pushed upwards (as shown with the small arrows). As theliquid is stirred by the vanes 2 up the side of the inner wall of theprimary chamber 1, the fluid eventually meets the upper inner edge ofthe primary chamber 1, and thus the direction of the fluid is redirectedinwardly towards the center of the primary chamber (as shown by thechange in direction of the small arrows in FIG. 3B). Thus, the positionof the inlet 5 is arranged so as to meet the direction of a part of thefluid flow in the primary chamber. In the embodiment of FIG. 3B, theupper inner edge is curved to enhance the re-direction of the fluidtowards the location of the inlet 5.

Varying Resistance by Varying Amount of Fluid in Secondary Chamber

When fluid is in the secondary chamber 3, it is effectively taken out ofthe flow region of the primary chamber 1. Hence, to increase theresistance, more fluid is kept in the primary chamber 1, with less beingin the secondary chamber 3. And vise versa, to reduce the resistance,less fluid is kept in the primary chamber 1, with more being in thesecondary chamber 3.

Although it is the amount of fluid in the primary chamber 1 thatdetermines the degree of resistance, the control of that resistance isachieved by controlling the fluid level in the secondary chamber 3.

The user can select the fluid level in the secondary chamber 3. Theoutlet 6 is controlled by a variation-means which provides a controlleror device to enables the user to select the amount of fluid retained inthe secondary chamber 3. The variation-means variably controls the flowof liquid through the outlet 6. The variation means variably controlsthe flow of liquid through the circuit to selectively establishdifferent circuit-flow conditions, each corresponding to a differentamount of the fluid in the primary fluid chamber. This variation enablesthe user to select a different degree of resistance for the exercisemachine.

This ability to control the amount of fluid in the secondary chamber 3effectively gives the user the ability to control the amount of fluid inthe primary chamber 1. This is how the user controls the degree ofresistance provided by the device 100.

The variation-means includes an outlet valve that controls the amount offluid that leaves the secondary chamber 3. An example of a valve isshown in FIGS. 1A-C, 3A and 3B. However, before describing the exampleof the valve in detail, the broad concept of the valve is conceptuallyexplained as follows:

Imagine a cylinder with a hole in a side wall. (The cylinder mentionedin this paragraph, of course, is not part of the present description ofembodiments, and is merely mentioned as an aid for explaining aconcept). Even if there is a continual fluid flow into the cylinder, thefluid level in the cylinder never rises above the height of the hole,because the fluid leaves the cylinder at the height of the hole. Thus, arelatively constant fluid level, which is level with the height of thehole, can be maintained in the cylinder, simply because the flowingfluid cannot rise above the level of the hole. Consequentially, raisingor lowering the fluid level in the cylinder is achieved by eitherraising or lowering the height position of the hole in the wall of thecylinder.

This concept, in the above paragraph, generally explains the function ofthe exemplary valve in FIGS. 1A-C, 3A and 3B.

In FIG. 1C, the valve comprises an inner cylinder 8 which has antriangular opening which defines an inclined slit. The inner cylinder 8has a knob 4 for the user to rotate the cylinder 8. The inner cylinder 8rotates within an outer cylinder 9 which also has its ownsimilarly-shaped triangular opening 9, in FIGS. 1D and 1DD, show that byrotating the knob 4 of the inner cylinder 8, the user can select thedegree of overlap of the triangular openings 8B, 9B. In FIG. 1DD, thereis a substantial degree of overlap, so the lowermost level of the outlet6 is close to the bottom of the openings. Whereas in FIG. 1D, there is alesser degree of overlap, and so the lowermost level of the outlet 6 ispositioned at a greater height. Thus, by rotating the knob 4, the usercontrols the height of the outlet 6, which effectively allows the userto select the height of the fluid in the secondary chamber 3—whicheffectively allows control of the amount of fluid in the primary chamber1. The raising or lowering of the effective height of the opening 6results in a raising or lowering of the height of the storage volume ofthe secondary chamber 3.

In FIG. 1C, the outer cylinder 9 is fixed to the base of the secondarychamber 3 so that it fits over hole 18. Thus, fluid that leaves thesecondary chamber through the outlet 6 in the valve will drop throughhole 18 back into the primary chamber 1.

In a further embodiment, the rotating valve can be provided with anautomatic rotation mechanism, for instance, powered by an electricmotor, which can progressively increase or decrease the resistance overa stipulated period of time. For instance, the user might stipulate thatthe resistance is to increase from a first value to a second value overa period of 10 minutes. In an embodiment configured as a rowing machine,the degree of resistance can be changed in midstroke by moving a lever,or by the foregoing automated control. For instance, rowing coaches cantrain their rowing teams by providing progressively increasingresistance to simulate racing conditions.

In other embodiments, the variation-means may also includes a valve thatcontrols the size and therefore the amount of liquid entering the inlet5 (described below in the passage relating to the vertical or uprightembodiment).

Calibration

The side wall of secondary chamber 3, or the valve is provided with agraduated series of markings, to allow the user to measure the liquidlevel in the secondary chamber 3.

The resistance device can be calibrated by operating the rotationaldevice at a known rotational rate (r. p. m.), and then gauging theliquid level that is established in the secondary chamber 3 for thatparticular known rotational rate.

The rotational speed (r. p. m.) of the device may be monitoredelectronically. In this</RTI> manner, a series of markings can beascertained that correspond to a range of rotational rates.

A factor that enables the device 100 to be calibrated accurately is thatthe amount of fluid in the overall device is known. As mentioned above,for instance, if the overall fluid amount is 10 litres, then the amountof fluid in the primary chamber 1 is the difference between 10 litresand the number of litres in the secondary chamber 3. Hence, there is aneed to periodically check that level of the total amount of fluid inthe overall device 100. This is best checked when the device is at rest.To facilitate the ability to check the total amount of fluid, thesecondary mechanism is provided with small openings that allow the waterto leak out at a very slow rate, so that, when the device is at rest,the fluid in both the primary and secondary chambers can reach arest-equilibrium level. The openings, in the embodiment, include thevery slight gaps between the wall surfaces of the inner and outercylinders 8,9. The openings may also comprise small holes in the sidewall of the secondary chamber that allow fluid to seep out over anextended period of time when the resistance device 100 is at rest. It isemphasised that these openings are so small that they do not play anysubstantial part in the flow of fluid around the fluid flow circuit, andthus are not regarded as inlets and/or outlets. Thus, when the liquidreaches an restequilibrium level, as a result of the liquid levelseeping through the openings, the user can obtain an indication of thetotal amount of liquid in the device 100. The sides of the primarychamber 1 may be provided with calibrated markings, so that the if theequilibrium-rest liquid level falls, perhaps due to evaporation, theliquid level can be topped up.

Advantage of the Fluid Flow Circuit

Fluid flows around this circuit only in this one general direction, asdescribed above. In other words, the fluid only enters the secondarychamber 3 through the inlet 5 in one direction, and only leaves thesecondary chamber at the height of outlet 6 in one direction. This“one-way flow” of fluid around the circuit is what gives the fluid flowthe characteristic of a “circuit”.

This is an important feature of the invention because, in this manner,the fluid is able to cycle within the circuit under the force ofgravity, aided by the turbulence caused by the rotating vanes 2. Thereis no need to expend energy to work against this natural circuit flowcycle, which would indeed be the case if it were attempted to cause thefluid to flow against this natural cycle.

In contrast to the present embodiments, some of the prior art areincapable of replicating this advantage. For instance, in U.S. Pat. No.5,944,637 (Stickler) in the prior art FIG. 10, fluid is forced in andout of a type of secondary chamber (87) through apertures 92 and 94. Inthat prior art, energy must be exerted to force the fluid in and out ofthe prior art secondary chamber (87). A similar deficiency is found inU.S. Pat. No. 5,195,936 (Mao) in the prior art FIG. 7, in which asprocket wheel (38) is required for force fluid in and out of a type ofsecondary chamber, being in the form of a fluid bag 37. In either pieceof prior art, there is an absence of a natural circuit flow cycle. Thisneed, in the prior art, for apparatus to force fluid in and out throughthe same openings means, adds to the cost and complexity of the knownapparatus, and also means that the user must exert greater effort inselecting a different degree of resistance.

Moreover, in the Mao prior art particularly, it takes a relatively longtime to squeeze the fluid out of the fluid bag 37, whereas in thepresent embodiment the user simply has to rotate the knob 4 and can thenre-commence exercising while the resistance device 100 adapts to thenewly selected degree of resistance.

Thus the user is able to change the resistance level with one quickrotation of a knob 4, and the natural flow of the circuit flow conditionadapts to create a new level of fluid in the secondary chamber 3, andhence the primary chamber 1.

In the present embodiment, as the fluid flows around the circuit, theuser can select the degree of resistance simply by rotating the knob 4.By doing this, the user effectively selects the amount of fluid that iscontained in the primary fluid chamber 1 (as explained above).

Gauging the Degree of Resistance

As the vanes 2 rotate about the spindle 30, the fluid in the primarychamber 1 will be extremely turbulent. In spite of the turbulence, itcan be readily ascertained how much fluid is in the primary chamber, byreferring to the relatively calm fluid level in the secondary chamber 3.Thus, the fluid level in the secondary chamber 3 provides an accurateindication of the amount of fluid in the primary chamber 1. In order tocontrol the amount of fluid in the secondary chamber 3, the user simplyhas to change the height of the outlet 6.

In contrast to prior art resistance devices, such as those which usemagnets or wind resistance, the level of fluid in the secondary chamber3 provides an accurate and, importantly, a repeatable measure of theresistance of the exercise machine.

In embodiments, the degree of resistance is highly repeatable for thelife of the apparatus. In the exemplary embodiment, there are nomagnetic or electronic parts to move out of alignment or lose magnetism.Also, there is no reliance on air density which can vary at differentaltitudes. The need for constant calibration is minimized, which tendsto be required in prior art systems that use friction belts, electronicand magnetic resistance mechanisms. In ergonometers that incorporateembodiments of the invention, the workload is able to be accuratelycalculated based on rotational speed (r. p. m.) of the device, and theamount of fluid present in the chambers. In such embodiments, there areno variables such as friction and heat, or variations in altitude forair systems, and no electromagnetic variables to could affect thesettings.

In the prior art, when wear and tear occurs over time, the calibrationof the magnetic resistance can alter from the original settings. In thecase of machines that use wind-resistance, the true resistance can varydepending on atmospheric pressure depending on the geographic altitude.In contrast, in the present embodiment, relying on the fluid level ofthe secondary chamber 3 as a indication of resistance is not as subjectto such variation, even when the machine has been used for a longperiod.

The calibration of the machine, described above, is dependent on factorsthat can be controlled, independent of the machine, for instance theknown rotational calibrating speed. Also, the calibration is determinedby the liquid level in the secondary chamber 3, which is unlikely to besignificantly influenced by normal wear and tear of the presentapparatus embodiment.

Embodiments With Whirlpool Effect

In the horizontal configuration in FIGS. 3A, 3B, 7, and 12A, as thevanes 2 rotate about the spindle 30, there is the possibility of awhirlpool being created in the central portion of the primary chamber 1.Whether or not a whirlpool is actually formed, depends on the height ofthe gap A shown in FIGS. 3C and 12A.

If the gap A is of sufficient height, there is sufficient space for awhirlpool to form in the centre of the primary fluid chamber 1. A fluidwhirlpool to be created under the secondary chamber 3 when the fluidswirls in the primary fluid flow region. Since the primary fluid flowregion is circular, the whirlpool is able to continue swirling freelyeven after cessation of the input from the exercise machine to therotation mechanism. It is unlikely that a whirlpool could be generatedin a non-circular flow region.

However, if the height of the gap A is very short, there is lesstendency for a whirlpool to be created. The significance of thewhirlpool is that the momentum of the swirling fluid would continue torotating urge the vanes 2 around the spindle, even when the rotationalinput from the exercise machine ceases, i. e. when the user stopsworking at the exercise machine.

In the horizontal embodiment, the whirlpool effect is a preferredfeature because it ensures that momentum of the rotating vanes 2 ismaintained for a period, even when the user's rotational inputs stopsfor a moment. For instance, when the user of an exercise bicycle stopspedaling for a few seconds, the presence of momentum ensures that whenthe user resumes pedaling, there is no need to start the rotation of thevanes from a stationery start. In other words, the user can resumepedaling roughly with the same sense of resistance as when he stopped.Since the momentum is maintained due to the swirling whirlpool, suchembodiments do not require heavy flywheels, which would be otherwiserequired to maintain a physical momentum flywheel.

Not all embodiments of the present invention have the whirlpool effect,but in those that do, the continued swirling of the fluid in the primarychamber 1, i. e. the whirlpool, can properly be regarded as a “liquidflywheel” because it is the movement of the liquid, itself, that isprimarily responsible for keeping the vanes rotating. The vanes 2 aremerely following the motion of the swirling fluid.

Embodiments Without Whirlpool Effect

If there is no momentum to keep the vanes 2 rotating, when the userresumes pedaling, he must overcome the initial inertia of the stationaryvanes 2.

In embodiments where there is no whirlpool effect to keep the fluidrotating, the momentum can be maintained by forming the vanes from aheavy material, which will tend to keep rotating for a longer period inthe absence of the user's input from the exercise machine. In suchcases, it would be inappropriate to refer to this as a “liquid flywheel”since the liquid, by itself, would tend to slow down because of theabsence of the whirlpool. Thus, in cases where there is no whirlpoolformed, the momentum is generated by the movement of the heavy rotatingvanes 2, which act similarly to a “mechanical flywheel” known in theprior art; and not as a “liquid flywheel” which requires the gap A to besufficiently large to create a whirlpool.

In other embodiments, the whirlpool effect can also be minimised byproviding the inner surfaces of the primary chamber 1 and/or the outersurfaces of the secondary chamber 3 with baffles (not shown) to hinderthe flow of fluid.

When baffles are present, the swirling of the fluid is substantiallydampened once the rotational driving force of the vanes 2 ceases. Thus,the presence of baffles in the path of the primary fluid flow regionminimises or prevents a “liquid flywheel” from forming. A “liquidflywheel” assumes that the liquid would continue to rotate freely,whereas the presence of the baffles would effectively prevent that fromhappening. The baffles would effectively prevent free movement of liquidaround the circular primary chamber 1

Vertical or Upright Configuration

Another configuration where there is no whirlpool effect is when theprimary fluid chamber 1 is oriented upright, since there is nohorizontally-oriented circular flow region for the fluid to continueswirling.

In the simplified diagram of FIG. 12B, a modified embodiment is shown inwhich the primary fluid chamber 1 is arranged upright or vertically.However, the function of device in FIG. 12B has similarities to the onein FIG. 12A.

Other upright configurations are shown in FIGS. 4A, 4B, 5,6, 8,9, 10 and11.

In FIG. 12B, upon cessation of the rotational input from the exercisemachine, the fluid in the upright primary chamber 1 tends to drop andcollect on the bottom of the upright chamber 1. As can be seen in FIG.12B, the upright gap G, which is between the exterior of the secondarychamber and the interior surface of the primary chamber, acts as afurther path through which the fluid can quickly drop and collect on thebottom of the upright chamber 1. There is no liquid flywheel (wherewater continues would rotate under its own momentum in a circular manneraround the rim). Indeed, in the vertical embodiment, the opposite to aliquid flywheel occurs, because the water drops to the bottom of theprimary chamber. The water, collected at the bottom of the primarychamber 1 thereby acts as a body of fluid that hinders and ultimatelystops the rotation of the vanes 2. In examples of embodiments of thepresent apparatus, the vanes 2 cease rotation in about 3 to 4 secondsupon the user ceasing to provide rotational input, whereas in prior artdevices that rely on liquid-flywheels, the liquid in those prior artcases can continue to rotate or circle around the chamber under its ownmomentum for around 30 seconds. Thus the vertical or upright embodimentof the present invention cannot be regarded as a liquid flywheel.

In FIG. 12B, the spindle 30 is arranged generally horizontally. As thevanes 2 rotate about the spindle axis, the vanes 2 rotate through theprimary chamber 1 in a manner akin to the vanes of a river water wheel.The secondary chamber 3 is motionless with respect to the primarychamber 1.

As the vanes 2 rotate, the vanes churn up the fluid and sweep the fluidup to the upper reaches of the primary chamber 1, and then the fluidfalls back to the bottom of the chamber 1, all the time being driven bythe rotating vanes 2. As this continues, a portion of the fluid entersthe inlet 5 of the secondary chamber 3 causing the secondary chamber tofill up with fluid. In the vertical embodiment, the position of theinlet 5 is at or close to the top of the secondary chamber 3, such thatthe inlet 5 is in the general location where part of the fluid tends todrop down from the top of the upright primary chamber 1. Thus, even inthe upright embodiment, the position of the inlet 5 is arranged so as tomeet the direction of part of the fluid flow in the primary chamber Asin the case in the horizontal configuration of FIG. 12A, there are alsoa fluid flow circuit is established in the vertical configuration ofFIG. 12B, because fluid can leave the secondary chamber through outlet6.

Here, once again, the amount of fluid contained in the primary chamber 1is determined by the amount of fluid being retained in the secondarychamber 3.

More detailed illustrations of embodiments of the vertical configurationare shown in FIGS. 2A to 2C, and in FIGS. 4A to 4B. (In FIGS. 4A, 4B and5, the fluid is indicated with dotted shading).

In an example of the upright embodiment, the inlet 5 is positioned atthe top, or close to the top of the secondary chamber 3 so as to bepositioned in the best location to allow fluid from the primary chamber1 to enter the secondary chamber 3 via the inlet 5. However, in otherembodiments, an inlet 5 can be positioned elsewhere.

In FIG. 2C (middle diagram), the inlet 5 is shown as a simple circularhole, however, in other embodiments the shape can be modified to includeany shape that enables fluid to enter the secondary chamber in acontrolled manner.

Having described the simplified diagram of FIG. 12B, fuller illustrativedetails are shown in FIGS. 2A to 2C. FIG. 2A shows a fully assembledprimary chamber 1. FIG. 2B shows the primary chamber 1 surrounded by therotatable vanes 2. FIG. 2C shows the arrangement with the lid of theprimary chamber removed to reveal the secondary chamber 3, having anoutlet 6 incorporated in parts of a valve mechanism comprising first andsecond circular grooves 9A, 8A. (Note: in FIG. 2B as drawn, the uprightside walls of the primary chamber 1 and of the secondary chamber 3 havebeen omitted to reveal the other components, and only the base 12 of theprimary chamber is shown). In FIG. 2C, the knob 4 is provided with alever arm. Rotation of the knob 4 causes rotation of the plate 10. Theknob 4 is connected to the plate 10 via hole 14 in the lid.

The surface of the knob 4 can be provided with markings so that the usercan selectively turn the knob to achieve the desired degree ofresistance.

Another feature of the vertical embodiments is that, upon the userstopping the rotational input-for example, pedaling, rowing orotherwise-the flow of fluid around the chamber (that is providingresistance to the flywheel) will break apart to either side of theresistance chamber. This assists in stopping the rotation when theuser's input suddenly ceases. This feature makes the verticalembodiments particularly advantageous for rehabilitation work.

In other embodiments, the slope of the side wall of the primary chambercan be modified. For instance, in the embodiment in FIG. 12B, the sidewall slopes downwardly away from the inlet 5. In other modifications theside wall can slow downwardly towards the inlet 5, which would assist indirecting the liquid towards the inlet 5. In further variations, theside wall can be perfectly horizontal.

In other modifications, the shape of the inner secondary chamber 3 canbe crescent-shaped like a half-crescent-moon, with the curved portion ofthe crescent-shaped chamber facing downwards, with the flat portion ofsuch a chamber facing upwards. In other words, the inner secondarychamber 3 need not be perfectly circular. Hence, the inner surface ofthe primary chamber 1 has to be circular, but the actual shape of theinner chamber 3 can vary. In another modification, the inner chamber 3may be square-shaped.

In some examples of vertical embodiments, the inner surfaces of theprimary fluid chamber and/or the outer surfaces of the secondary fluidchamber may be provided with baffles to further hinder the flow of fluidin the primary fluid chamber. The resistance offered by the baffles addsto the resistance that comes from the frictional resistance provided bythe inner and outer surfaces, and which comes from the gravitationalresistance acting against the vanes 2 that lift the fluid.

As the liquid in the primary chamber 1 increases, this increase inliquid results in increased resistance to the rotation of the vanes 2that are rotatably housed in the primary chamber. Thus, an increase inliquid in the primary chamber is associated with a decrease in the timetaken for the vanes 2 to stop rotating when the user ceases providingrotational input. For example, on the lightest degree of resistance, i.e. the least amount of fluid in the primary chamber, the vanes 2 maytake some 10 to 20 seconds to stop rotating when the user ceasesproviding rotational input. As the liquid level in the primary chamber 1increases, there is a decrease in the time taken for the vanes 2 to stoprotating.

Other Modifications

The embodiments have been advanced by way of example only, andmodifications are possible within the scope of the invention as definedby the appended claims.

In some embodiments, the variation-means may include a valve thatcontrols fluid-flow through the inlet 5 which is entering the secondarychamber 3. As an example, in FIG. 2C, the valve (instead of havingtriangular openings) comprises a pair of circular grooves. The body ofthe secondary chamber 3 is provided with a first circular groove 9A,while a rotating plate 10 is provided with a second circular groove 8A.As the user rotates the plate 10 with respect to the secondary chamber3, the user is able to vary the height of the outlet 6, which is formedat the lowermost point of the parts where the grooves 8A, 9A intersect.On this rotating plate 10 is a sloping flange 16 that is adapted toincrementally block the inlet 5 to vary degrees. Hence, the degree ofrotation of the plate 10 will alter the degree to which the flange 16covers the inlet 5. In FIG. 2C, the flange 16 is arranged such that whenthere is a greater amount of fluid in the primary chamber 1, the inlet 5is closed to a greater degree. This ensures that, when there is agreater amount of fluid in the primary chamber 1, the inlet 5 is madesmaller, since the greater amount of primary fluid means there is morefluid attempting to enter the inlet 5, hence a lesser need for a largeinlet size 5.

FIG. 5 illustrates a modification where the secondary chamber 3 isexternal to the vertical primary chamber 1.

The components of the primary and secondary chambers 1,3, can be made ofmetal, plastics or the like, preferably of clear Perspex orpolycarbonate material so that the user can see the swirling liquidwithin the chambers. When transparent materials are used, the swirlingof the fluid in the chambers presents an attractive visible feature.

In another embodiment, the secondary chamber is external to a horizontalprimary chamber, which allows a whirlpool can be created in the centreof the primary chamber.

Although the variation-means as been described above as a mechanism thatraises or lowers the height position of the outlet means, othermodifications can use a variation-means that controls the flow of liquidthrough the outlet means by increasing or decreasing the flow-throughsize of the outlet.

In this embodiment, the preferred fluid is water, but other fluids suchas silicon can also be used. Also, the water or fluid can be colored forvisual effect.

In the drawings, the valve is positioned off-centre or off-axis of thesecondary chamber, but it can also be positioned co-axially.

The shape of the vanes 2 can be varied, so long as these provide a formof paddle that can sweep against the fluid in the primary chamber 1.

The overall diameter of the rotation mechanism can be varied.

In the embodiments, the secondary mechanism includes one secondarychamber 3, but other embodiments can incorporate two or more secondarychambers.

The device may be provided with cooling devices for cooling the fluid.

In an embodiment of another aspect of the invention, a reciprocatingmechanism is positioned and adapted to reciprocate within the primaryfluid flow region such that the reciprocating mechanism uponreciprocation encounters a degree of resistance dependent on the amountof fluid in the primary fluid chamber, the reciprocating mechanism beingadapted to be reciprocate by mechanical input from the exercise machine.Here, the primary and secondary chambers need not be circular, but canbe any shape adapted to accommodate the reciprocating mechanism.

In other embodiments, a pumping mechanism, such as a pump, can be usedto assist or create the flow of fluid around the fluid flow circuit.

The concept of a fluid flow circuit excludes any prior art in whichfluid enters and leaves a chamber via the same opening since this cannotstrictly be regarded as a “circuit”.

In the illustrated embodiments, the secondary chamber is shown with afrusto-conical-like shape, however, the shape of the secondary chambercan be modified to have upright walls, for example.

In the embodiments, the gap between the outer edge of the vanes 2, andthe inner surface of the primary chamber 1, is around 0.25 inch or 5-6mm.

However, some experimentation can be done to determine an appropriategap size.

The rotation device in the embodiments are shaped as vanes, however,other embodiments can include blade-shaped paddles or other shapes thatcan act as a rotatable resistance mechanism.

References to prior art in the body of this specification are not to betaken as an admission that any of the prior art form part of the commongeneral knowledge of the skilled addressee of this invention.

1. A variable resistance device adapted to be incorporated if anexercise machine to provide selectively-variable resistance therefor,the device including: a primary fluid chamber adapted to receive fluidtherein, the primary chamber having a primary fluid flow region; arotation mechanism positioned and adapted to rotate within the primaryfluid flow region such that the rotation mechanism upon rotationencounters a degree of resistance dependent on the amount of fluid inthe primary fluid chamber, the rotation mechanism being adapted to berotated by rotational input from the exercise machine; a secondarymechanism adapted to achieve and maintain an appropriate amount of thefluid in the primary fluid chamber to provide a selected degree ofresistance for the exercise machine, the secondary mechanism having asecondary fluid flow region; a fluid flow circuit, which includes saidprimary and secondary fluid flow regions, through which circuit thefluid flows to establish a circuit-flow condition that repetitivelycycles around the circuit from the primary fluid flow region into thesecondary fluid flow region and then back into the primary fluid flowregion, the circuit-flow condition being adapted to establish andmaintain said appropriate amount of fluid in the primary fluid chamberduring use; and a controller for variably controlling flow of fluidthrough the circuit to selectively establish different circuit-flowconditions each corresponding to a different appropriate amount of thefluid in the primary fluid chamber to provide a different degree ofresistance for the exercise machine.
 2. A device of claim 1 wherein thesecondary mechanism includes a secondary fluid chamber adapted toreceive fluid therein, the secondary fluid chamber having said secondaryfluid flow region.
 3. A device of claim 2 wherein the amount of fluid inthe primary fluid chamber is able to be ascertained by measuring thelevel of fluid in the secondary fluid chamber.
 4. A device of claim 2wherein the secondary fluid chamber is positioned externally to theprimary fluid chamber.
 5. A device of claim 2 wherein the secondaryfluid chamber is positioned internally within the primary fluid chamber.6. A device of claim 5 wherein the primary fluid flow region of theprimary fluid chamber is defined by inner surfaces of the primary fluidchamber and by outer surfaces of the secondary fluid chamber.
 7. Adevice of claim 6 wherein the inner surfaces of the primary fluidchamber form a first circle, and the outer surfaces of the secondaryfluid chamber form a second circle which is concentric and c-axial withthe first circle, the primary fluid flow region being generally betweenthe two circles.
 8. A device of claim 7 wherein the primary fluid flowregion generally surrounds the secondary fluid chamber.
 9. A device ofclaim 7 wherein the primary fluid flow region is arranged substantiallyhorizontally.
 10. A device of claim 9 wherein the primary fluid flowregion further includes a space which is within the second circle andwhich is beneath the secondary fluid chamber, the space defining a gapbetween an external undersurface of the secondary fluid chamber and aninner surface of the primary fluid chamber.
 11. A device of claim 10wherein the gap is insufficient for a fluid whirlpool to be createdunder the secondary fluid chamber when the fluid flows in the primaryfluid flow region.
 12. A device of claim 2 wherein the primary fluidflow region is arranged generally upright.
 13. A device of claim 12wherein, in use, when the user provides the rotational input, the fluidmoves around the primary fluid flow region of the primary fluid chamberand also through the fluid flow circuit, and wherein, in use, when theuser ceases providing the rotational input, the fluid in theuprightly-oriented primary chamber falls to bottom of the primary fluidchamber thereby acting as a body of fluid that stops the rotation of therotation mechanism.
 14. A device of claim 7 wherein the inner surfacesof the primary fluid chamber and/or the outer surfaces of the secondaryfluid chamber is/are provided with baffles to hinder the flow of fluidin the primary fluid chamber.
 15. A device of claim 10 wherein the gapis sufficient for a fluid whirlpool to be created under the secondaryfluid chamber when the fluid swirls around in the primary fluid flowregion, the primary fluid flow region being shaped so that the whirlpoolis able to continue swirling freely even after cessation of the inputfrom the exercise machine to the rotation mechanism.
 16. A device ofclaim 1 wherein the secondary mechanism is provided with inlet meansthat allows fluid to flow from the primary flow region into thesecondary flow region.
 17. A device of claim 16 wherein fluid flowsthrough the inlet means exclusively in one direction.
 18. A device ofclaim 16 wherein the controller provides variation means for variablycontrolling the flow of fluid through the inlet means.
 19. A device ofclaim 16 wherein the position of the inlet means of the secondarymechanism is arranged so as to meet the direction of part of the fluidflow in the primary fluid flow region.
 20. A device of claim 1 whereinthe secondary mechanism is provided with outlet means that allows fluidto flow out of the secondary flow region back into the primary flowregion.
 21. A device of claim 20 wherein the controller providesvariation means for variably controllings the flow of fluid through theoutlet means.
 22. A device of claim 21 wherein the variation meansvariably controls the flow of fluid through the outlet means by raisingor lowering the height position of the outlet means.
 23. A device ofclaim 21 the variation means variably controls the flow of fluid throughthe outlet means by increasing or decreasing the flow-through size ofthe outlet means.
 24. A device of claim 1 wherein the fluid is water.25. A device of claim 1 wherein the fluid flow circuit is open to theatmosphere and is not of a hydraulic-nature.
 26. A device of claim 1wherein the fluid in the fluid flow circuit is substantially constant inamount.
 27. A device of claim 1 wherein the rotation mechanism isdirectly connected to the rotational input from the exercise machinewithout the need for a transmission and/or step-up system.
 28. A deviceof claim 1 wherein the exercise machine is an exercise bicycle.
 29. Adevice of claim 1 wherein the exercise machine is a rowing-simulatingexercise machine.
 30. An exercise machine incorporating a variableresistance device of claim
 1. 31. A device of claim 1 wherein atransmission arrangement is provided to alter the rate of rotation fromthe exercise machine such that the rotation mechanism receives adifferent rotational rate of input.
 32. A device of claim 1 wherein,instead of including the rotation mechanism, instead a reciprocatingmechanism is positioned and adapted to reciprocate within the primaryfluid flow region such that the reciprocating mechanism uponreciprocation encounters a degree of resistance dependent on the amountof fluid in the primary fluid chamber, the reciprocating mechanism beingadapted to be reciprocate by mechanical input from the exercise machine.33. A device of claim 1 wherein, in use, the fluid flows substantiallycontinuously between the primary and secondary chambers via the fluidflow circuit.
 34. A device of claim 1 wherein the amount of fluidcontained in the device remains substantially constant.
 35. A device ofclaim 1 wherein the rotation mechanism, upon rotation, encounters adegree of resistance dependent on the level of fluid in the primaryfluid chamber.
 36. A device of claim 1 wherein the secondary fluid flowregion is separate from the primary fluid flow region.
 37. A device ofclaim 1 wherein a pumping mechanism is used to assist or create the flowof fluid around the fluid flow circuit.
 38. A device of claim 32 whereinthe secondary mechanism is provided with outlet means that allows fluidto flow from the secondary flow region into the primary flow region. 39.A device of claim 36 wherein fluid flows through the outlet means of thesecondary mechanism exclusively in one direction.
 40. A device of claim1 wherein the rotation mechanism is in the form of rotatable vanes. 41.A variable resistance device adapted to be incorporated in an exercisemachine to provide selectively-variable resistance therefor, the deviceincluding: a primary circular fluid chamber adapted to receive fluidtherein, the primary chamber having a circular primary fluid flowregion; a rotation mechanism, which includes rotating vanes, beingpositioned and adapted to rotate within the primary fluid flow regionsuch that the rotation mechanism upon rotation encounters a degree ofresistance dependent on the amount of fluid in the primary fluidchamber, the rotation mechanism being adapted to be rotated byrotational input from the user via the exercise machine, the primaryfluid chamber being adapted to be positioned upright in use; a secondaryfluid chamber positioned substantially within the primary circular fluidchamber, the secondary fluid chamber being adapted to achieve andmaintain an appropriate amount of the fluid in the primary fluid chamberto provide a selected degree of resistance for the exercise machine, thesecondary chamber having a secondary fluid flow region, the secondarychamber being provided with an inlet positioned, in use, at orsubstantially close to the top of secondary chamber, the inlet allowingfluid to flow from the primary flow region into the secondary flowregion; a fluid flow circuit, which includes said primary and secondaryfluid flow regions, through which circuit the fluid flows to establish acircuit-flow condition that repetitively cycles around the circuit fromthe primary fluid flow region into the secondary fluid flow region andthen back into the primary fluid flow region, the circuit-flow condition